

If the rest of the household mostly uses the apps themselves rather than the server, the OS underneath matters less than it seems. I run plain Ubuntu Server and manage the containers with Komodo, which I moved to from Portainer: it gives me a web UI to see, restart and update stacks, while the compose files stay ordinary files I can back up. Since you already back up your configs and YAML, keeping compose underneath means the next dead SSD is a reinstall and a redeploy, not a migration out of someone’s app store.
Retired business or surveillance hardware is worth checking locally too. My two servers are repurposed NVRs running plain Ubuntu Server, and a Dell OptiPlex handles dev work. For that list, I’d start with the hardware you can get affordably and check its RAM capacity and drive connections before buying. Docker on plain Linux keeps things straightforward. With Immich, budget for a separate backup of the photos before it holds your only copy.